1. Technical Field
The present invention relates to a liquid droplet discharging method and a liquid droplet discharging apparatus.
2. Related Art
As a liquid droplet discharging apparatus of the related art, an ink jet printer is known in which liquid droplets (ink droplets) are discharged to a surface of print media to cause an image to be formed thereon. The ink jet printer includes a transport action where print media such as a paper or cloth is moved in a transporting direction, and a dot-forming action where a head in which a plurality of nozzles is formed is scan-moved in a scanning direction intersecting the transporting direction of the print media to cause ink droplets to be discharged from each nozzle. In the ink jet printer, the transport action and the dot-forming action are alternately repeated so as to cause rows of dots (dot rows), lined up in the scanning direction, to be formed in parallel in the transporting direction and thus an image is formed on the print media. In such an ink jet printer, in order to form a further highly refined image at high speed, a plurality of heads in which further minutely precise nozzles are arranged at high density is used.
In a case where a plurality of heads is used, there is a probability that the differences in ink discharging characteristics between each head causes color irregularity to be generated. As a technique for improving handling of the color irregularity, JP-A-2009-143135 proposes a method in which a correction result based on a correction value of ink discharging characteristics of each head is weighted according to a usage rate of the head for each dot row and thus the ink discharging quantity is corrected.
In the correction method described in JP-A-2009-143135, however, there is a problem in that in a case where there is a relative positional shift of a dot between a plurality of heads, it is difficult to appropriately correct the shift. Specifically, there is a problem in that, even in a case where a correction for each single head or a weighting correction according to a usage rate of the nozzles is appropriately performed, the relative positional shift of the dot causes the shift from the original color to be generated in an area where printing is performed by the plurality of heads. As a result, there is a problem in that the difference in colors is generated between an area where printing is performed by a single head and an area where printing is performed by the plurality of heads.